@Override
 public Boolean hasNonExpiredRental(Lendable lendable) {
   Rental myRental = getMyRental(lendable);
   return myRental != null ? !myRental.isExpired() : false;
 }
 @Override
 public boolean returnRentalForLendable(Lendable lendable) {
   Rental myRental = getMyRental(lendable);
   return myRental != null && !myRental.isExpired() ? myRental.returnToLibrary() : false;
 }